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<div class="refentry">
<a name="boost.proto._default.impl"></a><div class="titlepage"></div>
<div class="refnamediv">
<h2><span class="refentrytitle">Struct template impl</span></h2>
<p>boost::proto::_default::impl</p>
</div>
<h2 class="refsynopsisdiv-title">Synopsis</h2>
<div class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../../../proto/reference.html#header.boost.proto.transform.default_hpp" title="Header &lt;boost/proto/transform/default.hpp&gt;">boost/proto/transform/default.hpp</a>&gt;

</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <a class="link" href="../../../Expr.html" title="Concept Expr">Expr</a><span class="special">,</span> <span class="keyword">typename</span> State<span class="special">,</span> <span class="keyword">typename</span> Data<span class="special">&gt;</span> 
<span class="keyword">struct</span> <a class="link" href="impl.html" title="Struct template impl">impl</a> <span class="special">:</span> <span class="keyword"></span> <a class="link" href="../transform_impl.html" title="Struct template transform_impl">proto::transform_impl</a>&lt;Expr, State, Data&gt; <span class="special">{</span>
  <span class="comment">// <a class="link" href="impl.html#boost.proto._default.impltypes">types</a></span>
  <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">Expr</span><span class="special">::</span><span class="identifier">tag_type</span> <a name="boost.proto._default.impl.Tag"></a><span class="identifier">Tag</span><span class="special">;</span>          <span class="comment">// For exposition only</span>
  <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">see</span><span class="special">-</span><span class="identifier">below</span></em></span>               <a class="link" href="impl.html#boost.proto._default.impl.result_type"><span class="identifier">result_type</span></a><span class="special">;</span>

  <span class="comment">// <a class="link" href="impl.html#id-1_3_31_5_43_1_1_1_5_9-bb">public member functions</a></span>
  <span class="identifier">result_type</span> <a class="link" href="impl.html#id-1_3_31_5_43_1_1_1_5_9_1-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="keyword">typename</span> <span class="identifier">impl</span><span class="special">::</span><span class="identifier">expr_param</span><span class="special">,</span> 
                         <span class="keyword">typename</span> <span class="identifier">impl</span><span class="special">::</span><span class="identifier">state_param</span><span class="special">,</span> 
                         <span class="keyword">typename</span> <span class="identifier">impl</span><span class="special">::</span><span class="identifier">data_param</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>

  <span class="comment">// public data members</span>
  <span class="keyword">static</span> <span class="identifier">Expr</span> <span class="identifier">s_expr</span><span class="special">;</span>  <span class="comment">// For exposition only</span>
  <span class="keyword">static</span> <span class="identifier">State</span> <span class="identifier">s_state</span><span class="special">;</span>  <span class="comment">// For exposition only</span>
  <span class="keyword">static</span> <span class="identifier">Data</span> <span class="identifier">s_data</span><span class="special">;</span>  <span class="comment">// For exposition only</span>
<span class="special">}</span><span class="special">;</span></pre></div>
<div class="refsect1">
<a name="id-1.3.31.5.45.3.4.4.4"></a><h2>Description</h2>
<p>
              Let <code class="computeroutput"><code class="computeroutput">OP</code></code> be the C++ operator
              corresponding to <code class="computeroutput">Expr::proto_tag</code>. (For example, if
              <code class="computeroutput">Tag</code> is <code class="computeroutput">
              <a class="link" href="../tag/plus.html" title="Struct plus">proto::tag::plus</a></code>, let <code class="computeroutput">
              <code class="computeroutput">OP</code></code> be <code class="computeroutput">+</code>.)
            </p>
<p>
              The behavior of this class is specified in terms of the C++0x <code class="computeroutput">decltype</code>
              keyword. In systems where this keyword is not available, Proto uses the Boost.Typeof library to
              approximate the behavior.
            </p>
<div class="refsect2">
<a name="id-1.3.31.5.45.3.4.4.4.4"></a><h3>
<a name="boost.proto._default.impltypes"></a><code class="computeroutput">impl</code> 
        public
       types</h3>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<p>
<span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">see</span><span class="special">-</span><span class="identifier">below</span></em></span> <a name="boost.proto._default.impl.result_type"></a><span class="identifier">result_type</span><span class="special">;</span></p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
                    If <code class="computeroutput">Tag</code> corresponds to a unary prefix operator,
                    then the result type is
                    </p>
<pre class="programlisting"><span class="keyword">decltype</span><span class="special">(</span>
  <span class="identifier">OP</span> <span class="identifier">Grammar</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><a class="link" href="../child.html" title="Function child">proto::child</a><span class="special">(</span><span class="identifier">s_expr</span><span class="special">)</span><span class="special">,</span> <span class="identifier">s_state</span><span class="special">,</span> <span class="identifier">s_data</span><span class="special">)</span>
<span class="special">)</span></pre>
<p>
                  </p>
</li>
<li class="listitem">
<p>
                    If <code class="computeroutput">Tag</code> corresponds to a unary postfix operator,
                    then the result type is
                    </p>
<pre class="programlisting"><span class="keyword">decltype</span><span class="special">(</span>
  <span class="identifier">Grammar</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><a class="link" href="../child.html" title="Function child">proto::child</a><span class="special">(</span><span class="identifier">s_expr</span><span class="special">)</span><span class="special">,</span> <span class="identifier">s_state</span><span class="special">,</span> <span class="identifier">s_data</span><span class="special">)</span> <span class="identifier">OP</span>
<span class="special">)</span></pre>
<p>
                  </p>
</li>
<li class="listitem">
<p>
                    If <code class="computeroutput">Tag</code> corresponds to a binary infix operator,
                    then the result type is
                    </p>
<pre class="programlisting"><span class="keyword">decltype</span><span class="special">(</span>
  <span class="identifier">Grammar</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><a class="link" href="../left.html" title="Function left">proto::left</a><span class="special">(</span><span class="identifier">s_expr</span><span class="special">)</span><span class="special">,</span> <span class="identifier">s_state</span><span class="special">,</span> <span class="identifier">s_data</span><span class="special">)</span> <span class="identifier">OP</span>
  <span class="identifier">Grammar</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><a class="link" href="../right.html" title="Function right">proto::right</a><span class="special">(</span><span class="identifier">s_expr</span><span class="special">)</span><span class="special">,</span> <span class="identifier">s_state</span><span class="special">,</span> <span class="identifier">s_data</span><span class="special">)</span>
<span class="special">)</span></pre>
<p>
                  </p>
</li>
<li class="listitem">
<p>
                  If <code class="computeroutput">Tag</code> is <code class="computeroutput">
                    <a class="link" href="../tag/subscript.html" title="Struct subscript">proto::tag::subscript</a>
                  </code>,
                  then the result type is
                  </p>
<pre class="programlisting"><span class="keyword">decltype</span><span class="special">(</span>
  <span class="identifier">Grammar</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><a class="link" href="../left.html" title="Function left">proto::left</a><span class="special">(</span><span class="identifier">s_expr</span><span class="special">)</span><span class="special">,</span> <span class="identifier">s_state</span><span class="special">,</span> <span class="identifier">s_data</span><span class="special">)</span> <span class="special">[</span>
  <span class="identifier">Grammar</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><a class="link" href="../right.html" title="Function right">proto::right</a><span class="special">(</span><span class="identifier">s_expr</span><span class="special">)</span><span class="special">,</span> <span class="identifier">s_state</span><span class="special">,</span> <span class="identifier">s_data</span><span class="special">)</span> <span class="special">]</span>
<span class="special">)</span></pre>
<p>
                </p>
</li>
<li class="listitem">
<p>
                    If <code class="computeroutput">Tag</code> is <code class="computeroutput">
                      <a class="link" href="../tag/if_else_.html" title="Struct if_else_">proto::tag::if_else_</a>
                    </code>,
                    then the result type is
                    </p>
<pre class="programlisting"><span class="keyword">decltype</span><span class="special">(</span>
  <span class="identifier">Grammar</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><a class="link" href="../child_c.html" title="Function child_c">proto::child_c</a><span class="special">&lt;</span><span class="number">0</span><span class="special">&gt;</span><span class="special">(</span><span class="identifier">s_expr</span><span class="special">)</span><span class="special">,</span> <span class="identifier">s_state</span><span class="special">,</span> <span class="identifier">s_data</span><span class="special">)</span> <span class="special">?</span>
  <span class="identifier">Grammar</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><a class="link" href="../child_c.html" title="Function child_c">proto::child_c</a><span class="special">&lt;</span><span class="number">1</span><span class="special">&gt;</span><span class="special">(</span><span class="identifier">s_expr</span><span class="special">)</span><span class="special">,</span> <span class="identifier">s_state</span><span class="special">,</span> <span class="identifier">s_data</span><span class="special">)</span> <span class="special">:</span>
  <span class="identifier">Grammar</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><a class="link" href="../child_c.html" title="Function child_c">proto::child_c</a><span class="special">&lt;</span><span class="number">2</span><span class="special">&gt;</span><span class="special">(</span><span class="identifier">s_expr</span><span class="special">)</span><span class="special">,</span> <span class="identifier">s_state</span><span class="special">,</span> <span class="identifier">s_data</span><span class="special">)</span>
<span class="special">)</span></pre>
<p>
                  </p>
</li>
<li class="listitem">
<p>
                    If <code class="computeroutput">Tag</code> is <code class="computeroutput">
                      <a class="link" href="../tag/function.html" title="Struct function">proto::tag::function</a>
                    </code>,
                    then the result type is
                    </p>
<pre class="programlisting"><span class="keyword">decltype</span><span class="special">(</span>
  <span class="identifier">Grammar</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><a class="link" href="../child_c.html" title="Function child_c">proto::child_c</a><span class="special">&lt;</span><span class="number">0</span><span class="special">&gt;</span><span class="special">(</span><span class="identifier">s_expr</span><span class="special">)</span><span class="special">,</span> <span class="identifier">s_state</span><span class="special">,</span> <span class="identifier">s_data</span><span class="special">)</span> <span class="special">(</span>
  <span class="identifier">Grammar</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><a class="link" href="../child_c.html" title="Function child_c">proto::child_c</a><span class="special">&lt;</span><span class="number">1</span><span class="special">&gt;</span><span class="special">(</span><span class="identifier">s_expr</span><span class="special">)</span><span class="special">,</span> <span class="identifier">s_state</span><span class="special">,</span> <span class="identifier">s_data</span><span class="special">)</span><span class="special">,</span>
  <span class="special">...</span>
  <span class="identifier">Grammar</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><a class="link" href="../child_c.html" title="Function child_c">proto::child_c</a><span class="special">&lt;</span><span class="identifier">N</span><span class="special">&gt;</span><span class="special">(</span><span class="identifier">s_expr</span><span class="special">)</span><span class="special">,</span> <span class="identifier">s_state</span><span class="special">,</span> <span class="identifier">s_data</span><span class="special">)</span> <span class="special">)</span>
<span class="special">)</span></pre>
<p>
                  </p>
</li>
</ul></div>
</li></ol></div>
</div>
<div class="refsect2">
<a name="id-1.3.31.5.45.3.4.4.4.5"></a><h3>
<a name="id-1_3_31_5_43_1_1_1_5_9-bb"></a><code class="computeroutput">impl</code> public member functions</h3>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<pre class="literallayout"><span class="identifier">result_type</span> <a name="id-1_3_31_5_43_1_1_1_5_9_1-bb"></a><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><span class="keyword">typename</span> <span class="identifier">impl</span><span class="special">::</span><span class="identifier">expr_param</span> expr<span class="special">,</span> 
                       <span class="keyword">typename</span> <span class="identifier">impl</span><span class="special">::</span><span class="identifier">state_param</span> state<span class="special">,</span> 
                       <span class="keyword">typename</span> <span class="identifier">impl</span><span class="special">::</span><span class="identifier">data_param</span> data<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
<code class="computeroutput">
                <code class="computeroutput"><a class="link" href="../_default.html" title="Struct template _default">proto::_default</a></code>&lt;Grammar&gt;::impl&lt;Expr, State, Data&gt;::operator()
              </code><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
                    If <code class="computeroutput">Tag</code> corresponds to a unary prefix operator,
                    then return
                    </p>
<pre class="programlisting">OP Grammar()(<code class="computeroutput"><a class="link" href="../child.html" title="Function child">proto::child</a></code>(expr), state, data)</pre>
<p>
                  </p>
</li>
<li class="listitem">
<p>
                    If <code class="computeroutput">Tag</code> corresponds to a unary postfix operator,
                    then return
                    </p>
<pre class="programlisting">Grammar()(<code class="computeroutput"><a class="link" href="../child.html" title="Function child">proto::child</a></code>(expr), state, data) OP</pre>
<p>
                  </p>
</li>
<li class="listitem">
<p>
                    If <code class="computeroutput">Tag</code> corresponds to a binary infix operator,
                    then return
                    </p>
<pre class="programlisting">Grammar()(<code class="computeroutput"><a class="link" href="../left.html" title="Function left">proto::left</a></code>(expr), state, data) OP
Grammar()(<code class="computeroutput"><a class="link" href="../right.html" title="Function right">proto::right</a></code>(expr), state, data)</pre>
<p>
                  </p>
</li>
<li class="listitem">
<p>
                  If <code class="computeroutput">Tag</code> is <code class="computeroutput">
                    <code class="computeroutput"><a class="link" href="../tag/subscript.html" title="Struct subscript">proto::tag::subscript</a></code>
                  </code>,
                  then return
                  </p>
<pre class="programlisting">Grammar()(<code class="computeroutput"><a class="link" href="../left.html" title="Function left">proto::left</a></code>(expr), state, data) [
Grammar()(<code class="computeroutput"><a class="link" href="../right.html" title="Function right">proto::right</a></code>(expr), state, data) ]</pre>
<p>
                </p>
</li>
<li class="listitem">
<p>
                    If <code class="computeroutput">Tag</code> is <code class="computeroutput">
                      <code class="computeroutput"><a class="link" href="../tag/if_else_.html" title="Struct if_else_">proto::tag::if_else_</a></code>
                    </code>,
                    then return
                    </p>
<pre class="programlisting">Grammar()(<code class="computeroutput"><a class="link" href="../child_c.html" title="Function child_c">proto::child_c</a></code>&lt;0&gt;(expr), state, data) ?
Grammar()(<code class="computeroutput"><a class="link" href="../child_c.html" title="Function child_c">proto::child_c</a></code>&lt;1&gt;(expr), state, data) :
Grammar()(<code class="computeroutput"><a class="link" href="../child_c.html" title="Function child_c">proto::child_c</a></code>&lt;2&gt;(expr), state, data)</pre>
<p>
                  </p>
</li>
<li class="listitem">
<p>
                    If <code class="computeroutput">Tag</code> is <code class="computeroutput">
                      <code class="computeroutput"><a class="link" href="../tag/function.html" title="Struct function">proto::tag::function</a></code>
                    </code>,
                    then return
                    </p>
<pre class="programlisting">Grammar()(<code class="computeroutput"><a class="link" href="../child_c.html" title="Function child_c">proto::child_c</a></code>&lt;0&gt;(expr), state, data) (
Grammar()(<code class="computeroutput"><a class="link" href="../child_c.html" title="Function child_c">proto::child_c</a></code>&lt;1&gt;(expr), state, data),
...
Grammar()(<code class="computeroutput"><a class="link" href="../child_c.html" title="Function child_c">proto::child_c</a></code>&lt;N&gt;(expr), state, data) )</pre>
<p>
                  </p>
</li>
</ul></div>
</li></ol></div>
</div>
</div>
</div>
<div class="copyright-footer">Copyright © 2008 Eric Niebler<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
      </p>
</div>
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